/*
** $Id: liolib.c,v 2.72 2006/01/28 12:59:13 roberto Exp $
** Standard I/O (and system) library
** See Copyright Notice in lua.h
*/
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define liolib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"

#define IO_INPUT	1
#define IO_OUTPUT	2

static const char *const fnames[] = {"input", "output"};

static int
pushresult (lua_State *L, int i, const char *filename)
{
	int en = errno;  /* calls to Lua API may change this value */
	if (i) 
	{
		lua_pushboolean(L, 1);
		return 1;
	}
	else 
	{
		lua_pushnil(L);
		if (filename)
			lua_pushfstring(L, "%s: %s", filename, strerror(en));
		else
			lua_pushfstring(L, "%s", strerror(en));
		lua_pushinteger(L, en);
		return 3;
	}
}


static void 
fileerror (lua_State *L, int arg, const char *filename) 
{
	lua_pushfstring(L, "%s: %s", filename, strerror(errno));
	luaL_argerror(L, arg, lua_tostring(L, -1));
}


#define topfile(L)	((FILE **)luaL_checkudata(L, 1, LUA_FILEHANDLE))


static int 
io_type (lua_State *L)
{
	void *ud;
	luaL_checkany(L, 1);
	ud = lua_touserdata(L, 1);
	lua_getfield(L, LUA_REGISTRYINDEX, LUA_FILEHANDLE);
	if (ud == NULL || !lua_getmetatable(L, 1) || !lua_rawequal(L, -2, -1))
		lua_pushnil(L);  /* not a file */
	else if (*((FILE **)ud) == NULL)
		lua_pushliteral(L, "closed file");
	else
		lua_pushliteral(L, "file");
	return 1;
}


static FILE *
tofile (lua_State *L) 
{
	FILE **f = topfile(L);
	if (*f == NULL)
		luaL_error(L, "attempt to use a closed file");

	return *f;
}



/*
** When creating file handles, always creates a `closed' file handle
** before opening the actual file; so, if there is a memory error, the
** file is not left opened.
*/
static FILE **
newfile (lua_State *L) 
{
	FILE **pf = (FILE **)lua_newuserdata(L, sizeof(FILE *));
	*pf = NULL;  /* file handle is currently `closed' */
	luaL_getmetatable(L, LUA_FILEHANDLE);
	lua_setmetatable(L, -2);

	return pf;
}


/*
** this function has a separated environment, which defines the
** correct __close for 'popen' files
*/
static int
io_pclose (lua_State *L) 
{
	FILE **p = topfile(L);
	int ok = lua_pclose(L, *p);
	if (ok) *p = NULL;

	return pushresult(L, ok, NULL);
}


static int 
io_fclose (lua_State *L)
{
	FILE **p = topfile(L);
	int ok = (fclose(*p) == 0);
	if (ok) *p = NULL;

	return pushresult(L, ok, NULL);
}


static int 
aux_close (lua_State *L)
{
	lua_getfenv(L, 1);
	lua_getfield(L, -1, "__close");

	return (lua_tocfunction(L, -1))(L);
}


static int 
io_close (lua_State *L)
{
	if (lua_isnone(L, 1))
		lua_rawgeti(L, LUA_ENVIRONINDEX, IO_OUTPUT);
	tofile(L);  /* make sure argument is a file */

	return aux_close(L);
}


static int 
io_gc (lua_State *L) 
{
	FILE *f = *topfile(L);
	/* ignore closed files and standard files */
	if (f != NULL && f != stdin && f != stdout && f != stderr)
		aux_close(L);

	return 0;
}


static int
io_tostring (lua_State *L) 
{
	FILE *f = *topfile(L);
	if (f == NULL)
		lua_pushstring(L, "file (closed)");
	else
		lua_pushfstring(L, "file (%p)", f);

	return 1;
}


static int 
io_open (lua_State *L)
{
	const char *filename = luaL_checkstring(L, 1);
	const char *mode = luaL_optstring(L, 2, "r");
	FILE **pf = newfile(L);
	*pf = fopen(filename, mode);

	return (*pf == NULL) ? pushresult(L, 0, filename) : 1;
}


static int 
io_popen (lua_State *L) 
{
	const char *filename = luaL_checkstring(L, 1);
	const char *mode = luaL_optstring(L, 2, "r");
	FILE **pf = newfile(L);
	*pf = lua_popen(L, filename, mode);

	return (*pf == NULL) ? pushresult(L, 0, filename) : 1;
}


static int 
io_tmpfile (lua_State *L)
{
	FILE **pf = newfile(L);
	*pf = tmpfile();

	return (*pf == NULL) ? pushresult(L, 0, NULL) : 1;
}


static FILE *
getiofile (lua_State *L, int findex)
{
	FILE *f;
	lua_rawgeti(L, LUA_ENVIRONINDEX, findex);
	f = *(FILE **)lua_touserdata(L, -1);
	if (f == NULL)
		luaL_error(L, "standard %s file is closed", fnames[findex - 1]);

	return f;
}


static int
g_iofile (lua_State *L, int f, const char *mode) 
{
	if (!lua_isnoneornil(L, 1))
	{
		const char *filename = lua_tostring(L, 1);
		if (filename)
		{
			FILE **pf = newfile(L);
			*pf = fopen(filename, mode);
			if (*pf == NULL)
				fileerror(L, 1, filename);
		}
		else
		{
			tofile(L);  /* check that it's a valid file handle */
			lua_pushvalue(L, 1);
		}
		lua_rawseti(L, LUA_ENVIRONINDEX, f);
	}
	/* return current value */
	lua_rawgeti(L, LUA_ENVIRONINDEX, f);

	return 1;
}


static int
io_input (lua_State *L) 
{
	return g_iofile(L, IO_INPUT, "r");
}


static int 
io_output (lua_State *L) 
{
	return g_iofile(L, IO_OUTPUT, "w");
}


static int 
io_readline (lua_State *L);


static void 
aux_lines (lua_State *L, int idx, int toclose) 
{
	lua_pushvalue(L, idx);
	lua_pushboolean(L, toclose);  /* close/not close file when finished */
	lua_pushcclosure(L, io_readline, 2);
}


static int
f_lines (lua_State *L)
{
	tofile(L);  /* check that it's a valid file handle */
	aux_lines(L, 1, 0);
	return 1;
}


static int
io_lines (lua_State *L) 
{
	if (lua_isnoneornil(L, 1))	/* no arguments? */
	{  
		/* will iterate over default input */
		lua_rawgeti(L, LUA_ENVIRONINDEX, IO_INPUT);

		return f_lines(L);
	}
	else 
	{
		const char *filename = luaL_checkstring(L, 1);
		FILE **pf = newfile(L);
		*pf = fopen(filename, "r");
		if (*pf == NULL)
			fileerror(L, 1, filename);
		aux_lines(L, lua_gettop(L), 1);

		return 1;
	}
}


/*
** {======================================================
** READ
** =======================================================
*/


static int 
read_number (lua_State *L, FILE *f) 
{
	lua_Number d;
	if (fscanf(f, LUA_NUMBER_SCAN, &d) == 1)
	{
		lua_pushnumber(L, d);
		return 1;
	}
	else 
		return 0;  /* read fails */
}


static int 
test_eof (lua_State *L, FILE *f) 
{
	int c = getc(f);
	ungetc(c, f);
	lua_pushlstring(L, NULL, 0);

	return (c != EOF);
}


static int 
read_line (lua_State *L, FILE *f) 
{
	luaL_Buffer b;
	luaL_buffinit(L, &b);
	for (;;)
	{
		size_t l;
		char *p = luaL_prepbuffer(&b);
		if (fgets(p, LUAL_BUFFERSIZE, f) == NULL)  /* eof? */
		{ 
			luaL_pushresult(&b);  /* close buffer */
			return (lua_strlen(L, -1) > 0);  /* check whether read something */
		}
		l = strlen(p);
		if (l == 0 || p[l-1] != '\n')
			luaL_addsize(&b, l);
		else 
		{
			luaL_addsize(&b, l - 1);  /* do not include `eol' */
			luaL_pushresult(&b);  /* close buffer */

			return 1;  /* read at least an `eol' */
		}
	}
}


static int 
read_chars (lua_State *L, FILE *f, size_t n)
{
	size_t rlen;  /* how much to read */
	size_t nr;  /* number of chars actually read */
	luaL_Buffer b;
	luaL_buffinit(L, &b);
	rlen = LUAL_BUFFERSIZE;  /* try to read that much each time */
	do
	{
		char *p = luaL_prepbuffer(&b);
		if (rlen > n) rlen = n;  /* cannot read more than asked */
		nr = fread(p, sizeof(char), rlen, f);
		luaL_addsize(&b, nr);
		n -= nr;  /* still have to read `n' chars */
	} while (n > 0 && nr == rlen);  /* until end of count or eof */
	luaL_pushresult(&b);  /* close buffer */

	return (n == 0 || lua_strlen(L, -1) > 0);
}


static int 
g_read (lua_State *L, FILE *f, int first)
{
	int nargs = lua_gettop(L) - 1;
	int success;
	int n;
	clearerr(f);
	if (nargs == 0)	  /* no arguments? */
	{
		success = read_line(L, f);
		n = first+1;  /* to return 1 result */
	}
	else	 /* ensure stack space for all results and for auxlib's buffer */
	{ 
		luaL_checkstack(L, nargs+LUA_MINSTACK, "too many arguments");
		success = 1;
		for (n = first; nargs-- && success; n++)
		{
			if (lua_type(L, n) == LUA_TNUMBER) 
			{
				size_t l = (size_t)lua_tointeger(L, n);
				success = (l == 0) ? test_eof(L, f) : read_chars(L, f, l);
			}
			else 
			{
				const char *p = lua_tostring(L, n);
				luaL_argcheck(L, p && p[0] == '*', n, "invalid option");
				switch (p[1]) 
				{
				case 'n':  /* number */
					success = read_number(L, f);
					break;
				case 'l':  /* line */
					success = read_line(L, f);
					break;
				case 'a':  /* file */
					read_chars(L, f, ~((size_t)0));  /* read MAX_SIZE_T chars */
					success = 1; /* always success */
					break;
				default:
					return luaL_argerror(L, n, "invalid format");
				}
			}
		}
	}
	if (ferror(f))
		return pushresult(L, 0, NULL);
	if (!success)
	{
		lua_pop(L, 1);  /* remove last result */
		lua_pushnil(L);  /* push nil instead */
	}

	return n - first;
}


static int 
io_read (lua_State *L) 
{
	return g_read(L, getiofile(L, IO_INPUT), 1);
}


static int
f_read (lua_State *L)
{
	return g_read(L, tofile(L), 2);
}


static int
io_readline (lua_State *L)
{
	FILE *f = *(FILE **)lua_touserdata(L, lua_upvalueindex(1));
	int sucess;
	if (f == NULL)  /* file is already closed? */
		luaL_error(L, "file is already closed");
	sucess = read_line(L, f);
	if (ferror(f))
		return luaL_error(L, "%s", strerror(errno));

	if (sucess) 
		return 1;
	else
	{  /* EOF */
		if (lua_toboolean(L, lua_upvalueindex(2))) {  /* generator created file? */
			lua_settop(L, 0);
			lua_pushvalue(L, lua_upvalueindex(1));
			aux_close(L);  /* close it */
		}
		return 0;
	}
}

/* }====================================================== */


static int
g_write (lua_State *L, FILE *f, int arg) 
{
	int nargs = lua_gettop(L) - 1;
	int status = 1;
	for (; nargs--; arg++)
	{
		if (lua_type(L, arg) == LUA_TNUMBER) 
		{
			/* optimization: could be done exactly as for strings */
			status = status &&
				fprintf(f, LUA_NUMBER_FMT, lua_tonumber(L, arg)) > 0;
		}
		else
		{
			size_t l;
			const char *s = luaL_checklstring(L, arg, &l);
			status = status && (fwrite(s, sizeof(char), l, f) == l);
		}
	}
	return pushresult(L, status, NULL);
}


static int
io_write (lua_State *L)
{
	return g_write(L, getiofile(L, IO_OUTPUT), 1);
}


static int
f_write (lua_State *L) 
{
	return g_write(L, tofile(L), 2);
}


static int 
f_seek (lua_State *L)
{
	static const int mode[] = {SEEK_SET, SEEK_CUR, SEEK_END};
	static const char *const modenames[] = {"set", "cur", "end", NULL};
	FILE *f = tofile(L);
	int op = luaL_checkoption(L, 2, "cur", modenames);
	long offset = luaL_optlong(L, 3, 0);
	op = fseek(f, offset, mode[op]);
	if (op)
		return pushresult(L, 0, NULL);  /* error */
	else 
	{
		lua_pushinteger(L, ftell(f));
		return 1;
	}
}


static int 
f_setvbuf (lua_State *L)
{
	static const int mode[] = {_IONBF, _IOFBF, _IOLBF};
	static const char *const modenames[] = {"no", "full", "line", NULL};
	FILE *f = tofile(L);
	int op = luaL_checkoption(L, 2, NULL, modenames);
	lua_Integer sz = luaL_optinteger(L, 3, LUAL_BUFFERSIZE);
	int res = setvbuf(f, NULL, mode[op], sz);

	return pushresult(L, res == 0, NULL);
}



static int 
io_flush (lua_State *L) 
{
	return pushresult(L, fflush(getiofile(L, IO_OUTPUT)) == 0, NULL);
}


static int 
f_flush (lua_State *L)
{
	return pushresult(L, fflush(tofile(L)) == 0, NULL);
}


static const luaL_Reg iolib[] = 
{
	{"close", io_close},
	{"flush", io_flush},
	{"input", io_input},
	{"lines", io_lines},
	{"open", io_open},
	{"output", io_output},
	{"popen", io_popen},
	{"read", io_read},
	{"tmpfile", io_tmpfile},
	{"type", io_type},
	{"write", io_write},
	{NULL, NULL}
};


static const luaL_Reg flib[] = 
{
	{"close", io_close},
	{"flush", f_flush},
	{"lines", f_lines},
	{"read", f_read},
	{"seek", f_seek},
	{"setvbuf", f_setvbuf},
	{"write", f_write},
	{"__gc", io_gc},
	{"__tostring", io_tostring},
	{NULL, NULL}
};


static void 
createmeta (lua_State *L)
{
	luaL_newmetatable(L, LUA_FILEHANDLE);  /* create metatable for file handles */
	lua_pushvalue(L, -1);  /* push metatable */
	lua_setfield(L, -2, "__index");  /* metatable.__index = metatable */
	luaL_register(L, NULL, flib);  /* file methods */
}


static void 
createstdfile (lua_State *L, FILE *f, int k, const char *fname)
{
	*newfile(L) = f;
	if (k > 0) 
	{
		lua_pushvalue(L, -1);
		lua_rawseti(L, LUA_ENVIRONINDEX, k);
	}
	lua_setfield(L, -2, fname);
}


LUALIB_API int 
luaopen_io (lua_State *L)
{
	createmeta(L);
	/* create (private) environment (with fields IO_INPUT, IO_OUTPUT, __close) */
	lua_createtable(L, 2, 1);
	lua_replace(L, LUA_ENVIRONINDEX);
	/* open library */
	luaL_register(L, LUA_IOLIBNAME, iolib);
	/* create (and set) default files */
	createstdfile(L, stdin, IO_INPUT, "stdin");
	createstdfile(L, stdout, IO_OUTPUT, "stdout");
	createstdfile(L, stderr, 0, "stderr");
	/* create environment for 'popen' */
	lua_getfield(L, -1, "popen");
	lua_createtable(L, 0, 1);
	lua_pushcfunction(L, io_pclose);
	lua_setfield(L, -2, "__close");
	lua_setfenv(L, -2);
	lua_pop(L, 1);  /* pop 'popen' */
	/* set default close function */
	lua_pushcfunction(L, io_fclose);
	lua_setfield(L, LUA_ENVIRONINDEX, "__close");
	return 1;
}

